The invention relates to robots. More particularly, the invention relates to an overload protector for the attachment of a tool to a robot arm, in which the protector protects the robot arm against overload by pressure forces and tilting moments.
A device of this type is shown in German Offenlegungsschrift DE-OS No. 32 41 132. In this, the two elements are rigidly connected to the robot arm and the tool (or the tool holder) respectively. An axial compression spring is engaged between the two coupler elements, which are held together by retaining bolts. When the tool is subjected to forces which exceed those exerted by the pre-stressed spring, one side of the spring is compressed. This causes the tool axis to buckle relative to the axis of the robot arm. A detector element fastened to one element is then separated from an inductive proximity switch which is mounted in the other element. This produces a cut-off signal for the robot control system. The holding bolts engage co-axial holes in the other element and are tiltable with respect to it. At least one of the holding bolts has an enlarged spherical head which is tightly engaged in the corresponding hole in such a manner that there is no play between the head and the element and the head cannot rotate.